Is grounding the bridge thimble even necessary with proper shielding?

[alexpigment]

My wife bought me an MJT Candy Tangerine JM body for my birthday, and fortunately I had enough parts lying around to build the whole guitar. After initially putting it together, it was noisy as expected when not touching the strings, because there's not shielding paint on MJT bodies. I then did a pretty admirable job of shielding the cavities and the pickguard, and now there is no difference in noise level between touching the strings and not touching them, even with pretty heavy gain. In this scenario, is there any need to ground the bridge thimbles? It seems like it would only make a difference if there were noise that goes away when touching the strings.

I should note that I totally get the idea of "just do it", and in this case i have already *done it*, but I figured I'd offer up this question as a starting point for discussion. It's more of an academic question than a practical one.

[andy_tchp]

Something needs to ground the strings, so if there’s no wire from the vibrato to ground, the answer is yes.

[DrippyReverbTremolo]

To put it differently, if your body is the ground wire you are at risk of getting shocked.

People have died from getting zapped by a faulty microphone while playing a guitar that was not properly grounded. I would imagine the same goes for short-circuiting amps.

[timtam]

To put it differently, if your body is the ground wire you are at risk of getting shocked.

People have died from getting zapped by a faulty microphone while playing a guitar that was not properly grounded. I would imagine the same goes for short-circuiting amps.

This was a much greater topic of discussion, different opinions, and argument in the past. But a risky scenario is actually created by having a guitar with grounded strings. You (and your heart) become the electrically continuous path from a microphone to the "grounded" strings you're touching to potentially faulty mains grounding at your amp. Such that disconnecting or avoiding a bridge ground to ground the strings would actually be protective. A capacitor rated to 400v in the guitar was sometimes suggested as better protection against some but not all potential shock scenarios. But since serious accidents have been rare in recent years, most players are either unaware of the risk or regard the capacitor as too much of a PITA to bother with. The fact that one of the main proposers of this strategy also advocated "star grounding" to prevent (non-existent) hum-generating ground loops detracted from his overall credibility on the issue. The further fact that no guitar manufacturer AFAIK has deemed that mod necessary also didn't help. So the safest approach in a wired rig remains somewhat unclear. A mains tester on the power input to your mains gear is probably a good idea.
https://guitarnuts2.proboards.com/page/ ... ck-hazards
https://guitarnuts2.proboards.com/page/gn1-qtb

In short, it's an exaggeration to think of grounded strings as protection against electric shock. If you want that protection, use a wireless system and don't touch anything else on stage (including other members of your band).

Grounded strings are mainly to ground your big body noise antenna.

[DrippyReverbTremolo]

Thanks for that well informed reply. I may stand corrected.

I am however not picking up an acoustic.

[alexpigment]

This was a much greater topic of discussion, different opinions, and argument in the past. But a risky scenario is actually created by having a guitar with grounded strings. You (and your heart) become the electrically continuous path from a microphone to the "grounded" strings you're touching to potentially faulty mains grounding at your amp. Such that disconnecting or avoiding a bridge ground to ground the strings would actually be protective. A capacitor rated to 400v in the guitar was sometimes suggested as better protection against some but not all potential shock scenarios. But since serious accidents have been rare in recent years, most players are either unaware of the risk or regard the capacitor as too much of a PITA to bother with. The fact that one of the main proposers of this strategy also advocated "star grounding" to prevent (non-existent) hum-generating ground loops detracted from his overall credibility on the issue. The further fact that no guitar manufacturer AFAIK has deemed that mod necessary also didn't help. So the safest approach in a wired rig remains somewhat unclear. A mains tester on the power input to your mains gear is probably a good idea.
https://guitarnuts2.proboards.com/page/ ... ck-hazards
https://guitarnuts2.proboards.com/page/gn1-qtb

In short, it's an exaggeration to think of grounded strings as protection against electric shock. If you want that protection, use a wireless system and don't touch anything else on stage (including other members of your band).

Grounded strings are mainly to ground your big body noise antenna.

The first link was pretty enlightening, and actually does make the case to *not* ground the strings via the bridge, albeit under the assumption of a rare electrical risk in modern times. The second link went off the rails a bit, and also falls into the common mistake of misunderstanding what shielding does/doesn't do (particularly at the beginning and end). It feels like half of the people who talk about this sort of stuff on the internet have never done a single A/B test. Either that, or their guitar is sitting on a workbench and the strings aren't being touched at all, leading to incorrect conclusions.

I agree that there's a lot of conflating of electrical risks based on guitar grounding with actual *amp* grounding. Despite all the focus (and money) on unmodified gear in the vintage collector market, there's a reason why old guitar amps get their power cable replaced immediately Thanks for chiming in. Your well-researched and insightful posts are appreciated as always.

[Dr Tony Balls]

To put it differently, if your body is the ground wire you are at risk of getting shocked.

Nope. Edit: there's not enough context to make this make sense. Your body needs to be the connection between two points at different electric potential, plain and simple.

This was a much greater topic of discussion, different opinions, and argument in the past. But a risky scenario is actually created by having a guitar with grounded strings. You (and your heart) become the electrically continuous path from a microphone to the "grounded" strings you're touching to potentially faulty mains grounding at your amp.

This is correct BUT would very rarely be encountered in the modern day because every amp, PA, what have you has a proper 3-prong plug. So it needs to be a perfect storm of 1) playing a guitar while singing, and 2) either the guitar amp or PA having a faulty ground. And even then you're most likely getting hit with little stray voltages, not mains or HT levels.

If you dont ground the strings the whole damn thing is mostly just gonna buzz unless you're touching them.

[alexpigment]

If you dont ground the strings the whole damn thing is mostly just gonna buzz unless you're touching them.

With no shielding this is true. When a guitar is ideally shielded, however, there will be no change in buzz when touching the strings or not touching them. There are cases where it's difficult or impossible to adequately shield a guitar (like where a wire is run through a small channel that you can't shield). On a Jazzmaster, however, you have control of the whole wiring path without obstruction, since the entire wiring run is under the pickguard. I've got quite a few guitars where I can easily confirm that there is no change, and I do these tests with drive pedals on. There are other guitars (like a tele) where I can get close, but not perfect due to the particularities of those wiring runs. I suppose I could try shielded wiring runs to the output jack or from the neck pickup cavity, but it's never been a big enough issue for me to try.

EDIT: After re-reading the quoted sentence again, I feel like it's important to note that touching the strings won't have any effect *at all* if the bridge (or something that touches the strings) isn't grounded, regardless of whether the guitar is shielded or not. The "hum going away" is only because you're touching a grounded part of the guitar, whether that be the strings, a screw, the output jack, etc.

[Dr Tony Balls]

If you dont ground the strings the whole damn thing is mostly just gonna buzz unless you're touching them.

With no shielding this is true. When a guitar is ideally shielded, however, there will be no change in buzz when touching the strings or not touching them.

Incorrect. Shielding does nothing to ground the strings, only reduce noise.

If you dont ground the strings the whole damn thing is mostly just gonna buzz unless you're touching them.

EDIT: After re-reading the quoted sentence again, I feel like it's important to note that touching the strings won't have any effect *at all* if the bridge (or something that touches the strings) isn't grounded, regardless of whether the guitar is shielded or not.

Also incorrect. If the bridge is grounded, the strings are grounded, and the guitar works fine. Touching or not touching them has no effect. If the bridge is not grounded and you touch the strings your body may make adequate ground connection to eliminate the buzz, depending on enviroment, etc.

[alexpigment]

Incorrect. Shielding does nothing to ground the strings, only reduce noise.

I believe you read something in my post that isn't there. I didn't claim that shielding grounds the strings, either in the quoted text or elsewhere.

Also incorrect. If the bridge is grounded, the strings are grounded, and the guitar works fine. Touching or not touching them has no effect. If the bridge is not grounded and you touch the strings your body may make adequate ground connection to eliminate the buzz, depending on enviroment, etc.

If the strings aren't grounded, and therefore not electrically connected to anything that goes through the amp, why would your body touching them have any effect?

[Dr Tony Balls]

Incorrect. Shielding does nothing to ground the strings, only reduce noise.

I believe you read something in my post that isn't there. I didn't claim that shielding grounds the strings, either in the quoted text or elsewhere.

Perhaps I did but the point is that shielding or not, you need to ground the strings.

Also incorrect. If the bridge is grounded, the strings are grounded, and the guitar works fine. Touching or not touching them has no effect. If the bridge is not grounded and you touch the strings your body may make adequate ground connection to eliminate the buzz, depending on enviroment, etc.

If the strings aren't grounded, and therefore not electrically connected to anything that goes through the amp, why would your body touching them have any effect?

As stated, "your body may make adequate ground connection to eliminate the buzz, depending on enviroment, etc.".

[alexpigment]

As stated, "your body may make adequate ground connection to eliminate the buzz, depending on enviroment, etc.".

I'm interested in this theory. Please explain.

[alexpigment]

After Googling "why does a guitar bridge need to be grounded", some interesting posts came up:

https://electronics.stackexchange.com/q ... 068#649068

This is from an electrical engineer forum, and while I don't know how authoritative the author is for the book he's quoting, but it's interesting that there's a suggestion that bridge grounding was a "sloppy" substitute for lack of shielding in cheaper guitars. Obviously it's a rather oversimplified statement that doesn't take into account the practices of high end guitar builders, but it's an interesting perspective. If you read the other posts in the thread, there's an also a claim that grounding the bridge creates a shield around the pickups. I don't really feel like this holds water geometrically (i.e. there's no other 'end' to the shield like what's shown in the diagram), but sure, it's a theory and I won't discredit it without further research.

Of course, Lindy always comes up in Google searches, and here's a blog of his:

https://www.fralinpickups.com/2018/11/1 ... -grounding - specifically the heading "YOU GROUND OUT THE STRINGS:"

Grounding your strings is essential for having a quieter guitar. If you’ve ever noticed your guitar’s noise gets quieter when you touch the strings, you might have thought your body grounds your guitar’s parts. You’d be wrong if you did. It turns out, a human being makes a pretty good EMI (Electromagnetic Interference) antennae! Your body is an antenna for all sorts of EMI, so when you touch your guitar strings, the guitar is grounding you! Pretty cool, right?

Lindy definitely knows his stuff, but he has a habit of leaving out some details and using some incorrect terminology. The rest of the post talks about 'ground loops', but what he's actually saying is to not create *loops of ground connections* within a guitar, since it will create an antenna for interference. After wiring guitars for a few years, I've come to agree that things generally sound and work better when there are less wires. I'm fairly certain you don't need *any* physical ground wires on a Jazzmaster, but I still have one or two in there out of habit.

[sunburster]

If the either the bridge or the tremolo (choose one of these two) are not grounded, touching the strings won't remove the buzz, because there is no continuity between the strings and the electronics. I bought a Jaguar once that had the ground wire in the tremolo cavity come loose in transit and was no longer touching the metal. I knew right away this was the problem, because touching the strings, tremolo, bridge, or tuners did not eliminate the buzz. Once I fixed this issue, the buzz went away when I touched the strings or any of the aforementioned hardware.

[alexpigment]

If the either the bridge or the tremolo (choose one of these two) are not grounded, touching the strings won't remove the buzz, because there is no continuity between the strings and the electronics. I bought a Jaguar once that had the ground wire in the tremolo cavity come loose in transit and was no longer touching the metal. I knew right away this was the problem, because touching the strings, tremolo, bridge, or tuners did not eliminate the buzz. Once I fixed this issue, the buzz went away when I touched the strings or any of the aforementioned hardware.

That's basically the reason I started this thread. I was able to shield my new JM to the point where there was no buzz to go away when touching the bridge. That's not weird in my experience with JMs due to how the wiring is laid out in the guitar, but it did get me thinking about it (i.e. why do we ground the bridge). After some further research, it seems that the bridge ground is only necessary when shielding is inadequate. As I learned, the late 70s/early 80s Gibsons used some significant shielding techniques and omitted the bridge grounding wire as a result (and anecdotally people seem to think these are very quiet guitars when fully stock).